1. Field of the Invention
The present invention relates to an image processing apparatus, an image processing method, and a non-transitory computer readable storage medium having stored therein an image processing program.
2. Description of the Related Art
Conventionally, an image capturing technology called, for example, time slice or bullet time has been known. In this image capturing technology, a plurality of image capturing apparatuses (for example, cameras) are arranged around an image capturing target (for example, an object such as a person). Specifically, the image capturing apparatuses are arranged such that the optical axis of each image capturing apparatus passes through a predetermined one point of the image capturing target, and capture images of the object. An image generated by connecting image data captured by this image capturing technology is called, for example, a free viewpoint image. A user can select an optional viewpoint for the free viewpoint image, which allows visual recognition of the object at various angles. For example, when used for, for example, promotion, a free viewpoint image is likely to achieve a promotion effect stronger than that achieved by a normal image.
In a known technology (for example, Japanese Patent Application Laid-open No. 2007-286715) related to image capturing of an object, the object is recognized through image capturing when the object is on a sheet on which a marker as a feature point is printed. Literature of the conventional technology discloses that feature-point display medium information as information on a marker is recorded on the marker and specified through image recognition, which allows optional change of a condition in which the marker is used. For example, a method of processing of generating a free viewpoint image is disclosed as a technology related to a free viewpoint image (for example, Japanese Patent Application Laid-open No. 2014-239384 and Japanese Patent Application Laid-open No. 2015-127903).
However, with the above-described conventional technology (Japanese Patent Application Laid-open No. 2007-286715), it is difficult for a general user to effectively use a free viewpoint image. Specifically, the conventional technology according to the above-described Japanese Patent Application Laid-open No. 2007-286715 requires the use of a marker provided with an identifier or characteristic information. It is difficult for a general user to prepare such a marker and use the marker in image processing. Thus, with the conventional technology according to the above-described Japanese Patent Application Laid-open No. 2007-286715, it is difficult to promote usage of a free viewpoint image, such as easy generation of a free viewpoint image by a general user or presentation of the generated free viewpoint image to a third person.